These two angles (140° and 40°) are Supplementary Angles, because they add up to 180°. Notice that together they make astraight angle.
But the angles don’t have to be together. These two are supplementary because 60° + 120° = 180°

Complementary Angles

Two angles are Complementary when they
add up to 90 degrees (a Right Angle ).

These two angles (40° and 50°) are Complementary Angles, because they add up to 90°.Notice that together they make a right angle .
But the angles don’t have to be together. These two are complementary because 27° + 63° = 90°

Angle Relationships

Interior Angle

An Interior Angle is an angle inside a shape.

Exterior Angle

The Exterior Angle is the angle between any side of a shape, and a line extended from the next side.

Angles On One Side of A Straight Line

Angles on one side of a straight line will always add to 180 degrees.

If a line is split into 2 and you know one angle you can always find the other one.

30° + 150° = 180°

Interior Angles of Polygons

An Interior Angle is an angle inside a shape.

Triangles

The Interior Angles of a Triangle add up to 180°

90° + 60° + 30° = 180°	80° + 70° + 30° = 180°
It works for this triangle!	Let’s tilt a line by 10° … It still works, because one angle went up by 10°, but the other went down by 10°

Quadrilaterals (Squares, etc)

(A Quadrilateral has 4 straight sides)

90° + 90° + 90° + 90° = 360°	80° + 100° + 90° + 90° = 360°
A Square adds up to 360°	Let’s tilt a line by 10° … still adds up to 360°!
The Interior Angles of a Quadrilateral add up to 360°

Because there are Two Triangles in a Square

The interior angles in this triangle add up to 180° (90°+45°+45°=180°)

… and for this square they add up to 360° … because the square can be made from two triangles!